Along with the proposed research project, the training plan will address gaps in immunology training and aid in development of professional skills needed to become an independent research scientist. Didactic courses in immunology will address gaps in basic knowledge, while quarterly meetings with a mentoring team comprised of faculty members with a focus in vaccine research and immunology will help guide my work. Attending vaccine and immunology focused conferences and discussion of current topics in immunology with peers will further strengthen immunology skills needed to be successful in vaccine research. Additionally, feedback from quarterly meetings with a mentoring team, participation in several professional development workshops and programs, and presenting research at multiple conferences will aid in development of professional skills necessary to conduct independent research. Moraxella catarrhalis is a leading cause of otitis media and exacerbations of COPD, two diseases that cause tremendous human suffering and economic burden worldwide. PCR-based detection has revealed severe underestimation of M. catarrhalis in otitis media. Furthermore, the lack of identified correlates of protection against M. catarrhali and lack of groups working on this organism has contributed to the delay in the development of an M. catarrhalis vaccine. The proposed project will address this gap in the field by examining the role of humoral and cellular immunity against M. catarrhalis following vaccination with OppA, a promising vaccine antigen. Therefore, the goal of Aim 1 is to identify protective B cell responses by assessing the antibody response to OppA in humans and OppA-vaccinated animals; the goal of Aim 2 is to identify protective T cell responses in mice immunized with OppA. The completion of the proposed studies will advance the field and aid in development of an M. catarrhalis vaccine to prevent otitis media and exacerbations of COPD.